Patent GB-1018588-A (GB)
Title: Improvements in or relating to horizontal boring mills
IPC: G05B19/04
Filed: 1962-08-10
Abstract: 1,018,588. Boring mills. BULLARD CO. Aug. 10, 1962 [Aug. 10, 1961], No. 30758/62. Headings B3B and B3T. [Also in Division F2] In a horizontal boring mill, a saddle S<SP>1</SP>, worktable T and headstock H are movable in directions at right angles to each other and are driven through a steplessly variable hydromechanical gear VS and separate forwardreverse gears, the headstock transmission which drives the spindle S comprises three direct-reduced planet trains in series. Gearing.-The headstock planet gear which provides seven ratios in geometric progression is preceded by a forward-reverse gear B and a four-ratio non-planetary gear. The headstock planet gear and four ratio gear are controlled by a cam selector drum, Fig. 6 (not shown), driven from a reversible electric motor. A needle 688, Fig. 1 (not shown), fast with the selector drum indicates the spindle speed selected. The spindle S is driven axially through the steplessly variable speed gear VS, a forward reverse gear and a rack and pinion gear. The steplessly variable speed gear VS, Fig. 9 (not shown), comprises two planet trains D, E in parallel, the reaction rings of which are controlled by an hydraulic transmission 750, 752, the ratio of which is varied in response to axial movement of a cam-plate 820. For feed movement of the saddle, worktable or headstock the cam-plate may be positioned by turning a knob 942 which acts through a lever 946, piston and cylinder 947, 948 and a rod 950 on a lever 896 that engages on abutment 895 on the camplate 820 or may be adjusted automatically through a planet gear 841, a clutch 857<SP>1</SP> and rack and pinion gear 859, 860 to maintain the gear output speed proportional to the spindle speed. The sun gear 850<SP>1</SP> of the planet gear 841 is driven from the spindle S through a disc and roller friction gear 846, 847<SP>1</SP> at a speed proportional to the spindle speed whilst the ring gear 851<SP>1</SP> is driven from the output shaft 740 of the gear VS. When a predetermined relation exists between the speed of the spindle S and output shaft 740 the planet carrier 854<SP>1</SP> is stationary. A change in the spindle speed or output shaft speed causes the planet carrier to rotate and drive the cam-plate 820 which adjusts the output speed of the gear VS to restore the predetermined relation. The predetermined relation may be adjusted by varying the ratio of the disc and roller gear 846, 847<SP>1</SP> effected by turning a knob 867. For traverse movement of the saddle, worktable or headstock an electric motor 904 drives a cam 900 which acts through a follower 899 and shaft 897 to rotate the lever 896 and thus move the cam-plate 820. When the clutch 857<SP>1</SP> is disengaged a stop 892 projects into the path of a lever 888 connected to the camplate 820 and prevents the output speed of the gear falling below a predetermined creep speed. To start the headstock spindle S a pushbutton switch 968 on a remote hand held pendent P, Fig. 10 (not shown), is depressed. When the spindle S is rotating anticlockwise rotation of a trigger 868 of the pendent P operates valves supplying pressure fluid to the clutch 857<SP>1</SP> or cylinder 947, Fig. 9 (not shown). Movement of the saddle, table, headstock or axial movement of the spindle is selected by closing switches operating valves supplying pressure liquid to the saddle, table, headstock or spindle forward-reverse gears. For traverse movement of the saddle, table or headstock with the spindles stationary, the trigger 868, Fig. 11 (not shown), is moved clockwise to increase the speed of the gear VS. On still further movement of trigger 868 the gear VS provides maximum output speed. On release of trigger 686 the gear VS moves into the creep position determined by the stop 892.